1. Field of Invention
This invention belongs to the area of heat pump/refrigeration technology and the utilization of low-temperature waste heat.
2. Description of Related Arts
A permanent goal of heat pump units is higher performance coefficient (COP), structure as simple as possible and suitable operating parameters.
It can be seen from the heat pump units that each exothermic section corresponds to a thermal demand of the heated medium. The higher the exothermic section is, the higher the cost is that the units pay to increase the temperature of waste heat medium. Different exothermic section of the units has different effects on its COP. Heating section at low temperature has a higher COP while heating section at high temperature has a lower COP, which forms a completed performance of the heat pump units. Obviously, the heating section of the units should match the temperature range of heated medium to ensure higher COP. Given the residual heat resources and the actuated-hot resources, each heating section of the units has a corresponding temperature range and COP. Obviously the heating section should match the temperature range of heated medium.
It can be seen from the structure and process of the units that a complete process of absorption heat pump must have two exothermic sections in absorber and evaporator. When an exothermic process of heat pump (or two heating sections) can't meet the need of users and we only need one more heating section to satisfy the need, it not only makes the structure and process of the units more complex, but also makes the COP of the units much lower if we increase two exothermic sections in absorber and evaporator of a complete heat pump process. In other words, we should not add a complete heat pump process but a corresponding heating section to satisfy the heat demand of heated medium when the heat demand exceeds two exothermic sections in absorber and evaporator.
In reality, the heat demand of heated medium is optional. Adopting three-terminal heating can make the structure of units simple and get a high COP when two-terminal heating can't meet the need of users and four-terminal heating exceeds it.
Moreover, seen from the perspective of providing high-temperature heating, adding high-temperature heating-side can have different heating options. But they must satisfy the approaching principle. This principle is that it is reasonable to have a close technology between the aspect of promoting temperature and changing the COP and the existing process of heat pump. In other words, they must satisfy the requirements that it is adjacent between the additional of high-temperature heating-side and the heating-side of the existing heat pump.